function ajax({
    method,url,success
}){
    var xhr = new XMLHttpRequest();
    xhr.open(method,url,true);
    xhr.send();
    xhr.onreadystatechange = function(){
        if(xhr.readyState ==4 && xhr.status ==200){
            var result = JSON.parse(xhr.responseText);
            success(result)
        }
    }
}